中文摘要：

摘要：基于CIGRE高压直流输电基准模型和IEEESSR第一基准模型，利用PSCAD／EMTDC软件构造了仿真模型，研究次同步振荡及Hopf分叉现象。应用MATLAB软件，实现自动判别系统相对稳定性的功能。仿真说明：HVDC输电系统次同步振荡与HVDC控制器特性参数有内在联系。存在一个系统临界稳定参数，当参数超过该临界值时，系统失稳；当参数低于该临界值时，系统稳定。

英文摘要：

Based on the CIGRE HVDC benchmark model and the IEEE SSR first benchmark model, ttlis paper builds a simulation model by PSCAD/EMTDC to study the subsynchronous oscillation and Hopf bifurcation. And lhe rcdative stability of system is automatically identified by MATLAB. Simulation demonstrates that HVDC subsyn（＇hronoos ost.il- lations is related with the HVDC controller parameters. There is a critical stability parameter, and the system will be instable when controller parameters exceed it, but stable when below this threshold.